1. Field of the Invention
The present invention relates to the synthesis of deoxycholic acid and pharmaceutically acceptable salts and intermediates thereof.
2. State of the Art
Rapid removal of body fat is an age-old ideal, and many substances have been claimed to accomplish such results, although few have shown results. “Mesotherapy”, or the use of injectables for the removal of fat, is not widely accepted among medical practitioners due to safety and efficacy concerns, although homeopathic and cosmetic claims have been made since the 1950's. Mesotherapy was originally conceived in Europe as a method of utilizing cutaneous injections containing a mixture of compounds for the treatment of local medical and cosmetic conditions. Although mesotherapy was traditionally employed for pain relief, its cosmetic applications, particularly fat and cellulite removal, have recently received attention in the United States. One such reported treatment for localized fat reduction, which was popularized in Brazil and uses injections of phosphatidylcholine, has been erroneously considered synonymous with mesotherapy. Despite its attraction as a purported “fat-dissolving” injection, the safety and efficacy of these cosmetic treatments remain ambiguous to most patients and physicians. See, Rotunda, A. M. and M. Kolodney, Dermatologic Surgery 32: 465-480 (2006) (“Mesotherapy and Phosphatidylcholine Injections: Historical Clarification and Review”).
Recently published literature reports that the bile acid deoxycholic acid has fat removing properties when injected into fatty deposits in vivo. See, WO 2005/117900 and WO 2005/112942, as well as US2005/0261258; US2005/0267080; US2006/127468; and US20060154906, all incorporated herein by reference in their entirety including figures). Deoxycholate injected into fat tissue has the effects of 1) degrading fat cells via a cytolytic mechanism; and 2) causing skin tightening. Both of these effects are required to mediate the desired aesthetic corrections (i.e., body contouring). Because deoxycholate injected into fat is rapidly inactivated by exposure to protein and then rapidly returns to the intestinal contents, its effects are spatially contained. As a result of this attenuation effect that confers clinical safety, fat removal therapies typically require 4-6 sessions. This localized fat removal without the need for surgery is beneficial not only for therapeutic treatment relating to pathological localized fat deposits (e.g., dyslipidemias incident to medical intervention in the treatment of HIV), but also for cosmetic fat removal without the attendant risk inherent in surgery (e.g., liposuction). See, Rotunda et al., Dermatol. Surgery 30: 1001-1008 (2004) (“Detergent effects of sodium deoxycholate are a major feature of an injectable phosphatidylcholine formulation used for localized fat dissolution”) and Rotunda et al., J. Am. Acad. Dermatol. (2005: 973-978) (“Lipomas treated with subcutaneous deoxycholate injections”), both incorporated herein by reference.
Pharmaceutical grade bile acid preparations are commercially available at relatively low cost. This low cost is due to the fact that the bile acids are obtained from animal carcasses, particularly large animals such as cows and sheep. Importantly, as with all medicaments from animal sources, there is concern that the animal-derived bile acid products may contain animal pathogens and other harmful agents such as animal or microbial metabolites and toxins, including bacterial toxins such as pyrogens.
Currently, the concerns regarding animal-derived products containing animal pathogens and other harmful agents has been addressed by sourcing from isolated and inspected animals. For example, deoxycholic acid from animals in New Zealand are a source of bile acids for human use under US regulatory regimes, as long as the animals continue to remain isolated and otherwise free of observable pathogens.
There remains a need for suitable quantities of efficacious bile acids such as deoxycholic acids that are known from the outset to be free from moieties of animal origin (or pathogenic moieties capable of acting in an animal, particularly a mammal, and for human use, having a deleterious effect on a human), and other harmful agents such as animal or microbial metabolites, toxins, including bacterial toxins, such as pyrogens, for use as medicaments in humans.